Conventional reflectors and the methods of the preparation thereof can be classified as follows: Typical examples are
(1) those in which the surfaces of metals such as stainless steel or aluminum are buff-polished, electrolytically polished or chemically polished,
(2) those in which the surfaces of metals such as iron or aluminum are porcelain enameled,
(3) those in which glass plates or transparent resin plates are coated metals such as aluminum by vacuum deposition or silver by silver mirror reaction on the surfaces or back sides thereof and
(4) those in which transparent resin films are coated on the surfaces of (1) or (3) as above mentioned.
Those in (1), however, are made of metals, so that poor manufacturing flexibility arises corrosion occurs and, further more, polishing needs a great deal of labor. Additionally, on mechanical polishing such as buff-polishing, the finished surfaces are rough and the single metal surfaces are very difficult to produce light reflective properties. Electrolytic or chemical polishings, which are wet methods, have the disadvantage that not only do pollution problems of the chemicals used occur but also the light reflective properties on the polished surfaces are not good but are insufficient as mirror surfaces.
Those in (2) made of metals have disadvantages. Those in (1) and the porcelain-enameled surfaces do not have light reflectivity but diffused reflection and dispersed light are obtained, although the surfaces are smooth. Moreover, procelain enamels are fragile and thus not resistant to impact, and corrosion and erosion of metals occurs in the broken area. Since porcelain enamels have high specific gravities, they have many disadvantages such as heavy weight.
As to those in (3), the surfaces are of metals, and consequently, chemical their resistance, weatherability and abrasion resistance are bad and particularly those of glass are not only heavy and easily break, but also have poor total reflectivity. In the case of those electroplated with nickel or chromium, though they have good light reflectivity since conventional electroplating is a wet process, this process has the disadvantage of the environmental pollution problem in terms of the chemicals used.
Those in (4) are improved as to the disadvantage of (1) to (3) but heat resistance, abrasion resistance, light resistance, weatherability, chemical resistance, etc. of the protective resin films coated on the surfaces are trouble some problems. For example, the surfaces tend to be colored or devitrified, and the total reflectivity decreases or when the surfaces are wiped with a cloth, etc., to clean them, abrasion is often observed as as time passes. And since the protective resin films on the surfaces are formed by coating resin solutions and allowing the solvents to vaporize and solidify the resin films in production environmental pollution due to solvents occurs and, not only is an device for recovering solvents required but also, when the substrate resins, glass, etc., when the surfaces are not smooth but rough and have patterns, the coating is very difficult. For example, even if coating could be done, due to the sagging phenomenon of resin solutions and the filling of gaps of the non-smooth surfaces of the coating films with resin, not only total reflectivity but also light reflectivity detoriates very much due to the heterogeneous refraction or absorption of light due to the coated resin layers. Further, since the coating thickness of the coating is larger, those in (4) have many disadvantages. One of these disadvantages is that not only is absorption index of light is high but also the absorption of IR rays becomes high, and thus, the surface temperature rises and the above mentioned deterioration of the physical properties of the resin layers on the surfaces is accelerated.